Pipe coating apparatus



Aug. 30, 1966 Q. M. BLOOM PIPE COATING APPARATUS 2 Sheets-Sheet 1 Filed May 4, 1962 INVENTOR. QUENTIN M. BLOOM ATTORNEY.

2 Sheets-Sheet 2 Filed May 4. 1962 INVENTOR. QUENTIN M. BLOOM BY 2M1%2 w- ATTORNEY.

United States Patent 3,269,354 PIPE IGATING APPARATUS Quentin M. Bloom, Viilanova, Pa., assignor to Selas Corporation of America, a corporation of Pennsylvania Filed May 4, 1962, Ser. No. 192,417

6 Claims. (Cl. 118-67) The present invention relates to the coating of metals, and more particularly to an apparatus for coating pipes with a material such as zinc or aluminum, for example.

In the coating of metal, it is necessary to have the metal object at the correct temperature and to have the surface of the metal clean. These things can be accomplished without too much difficulty when the object being coated is a sheet, for example. The process is more difficult, however, when the object being coated is tubular, since obtaining a clean surface on the interior of the tube presents a number of problems.

It is an object of the present invention to provide an apparatus for coating both the inside and outside of pipe.

It is a further object of the invention to provide a means for heating pipe, or other tubular objects, in such a manner that the surfaces of the pipe are kept clean during the heating.

It is a further object of the invention to provide means for cooling a heated pipe, or othertubular object, in such a manner that the interior as well as the exterior of the pipe is protected from oxidation, which includes setting up a flow of atmosphere through the pipe.

In practicing the invention, the pipes are moved axially through an elongated furnace where they are heated under conditions and at a temperature to remove any oxides from the surface. The pipes are moved axially through a series of connected cooling units or chambers, each of which is at a successively higher pressure. Atmosphere being circulated in the units to cool the pipes moves from the higher pressure toward the lower pressure, and in so doing causes a stream to flow through the pipe to clean and protect its interior surface.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 shows diagrammatically the apparatus of the invention,

FIG. 2 is a section taken through the furnace,

FIG. 3 is a section taken through one of the cooling units on line 33 of FIG. 4, and

FIG. 4 is a longitudinal section of one of the cooling units on line 44 of FIG. 3.

In FIG. 1 there is shown diagrammatically a conveyor 1 which supplies pipe to be heated to a furnace 2 and a cooling apparatus 3 from which the pipe is delivered to a coating tank 4. The furnace and the cooling unit each have conveying rolls in them that form an extension of the conveyor 1 so that the pipe is moved in a path axially through the apparatus into the coating tank.

In FIG. 2 there is a section through the furnace, which can be of the barrel type. This furnace is mounted on a steel framework 5, which supports a furnace unit including a furnace chamber 6 that is formed of refractory 7 in the usual type of furnace construction. The furnace is heated by a plurality of :burners 8 which are preferably of the radiant cup variety as shown in Patent No. 2,855,- 033. As shown herein, each furnace has two grouos of three burners that are directed radially toward the work.

Also, as shown herein, the furnace is designed for heating simultaneously four tubes, although a different number could be heated, if desired, by merely changing the shape of the conveyor roll and the supply and discharge openings to the furnace. with a pair of exhaust stacks 9 through which the products of combustion from the :burners can be discharged.

Work is conveyed through the furnace by means of conveyor rolls that are supported in and protected by abutrnents 11 formed in chamber 6. Each conveyor roll consists of a shaft 12 that extends through the furnace chamber and the abutments, and is journaled for rotation in bearings 14. The shaft has attached to it a sleeve 13 which moves the work. It will :be seen that this sleeve is formed with four grooves in order to keep the pipes aligned axially as they are moving through the furnace. There is also provided a supply and drain fitting 15 through which cooling water for the shaft 12 can be supplied and discharged.

Cooling apparatus 3 includes a series of cooling units that are axially aligned to form a continuous and enclosed passage for the pipes as they are being moved toward the coating tank. Each cooling unit includes chamber 16, made of sheet metal, that surrounds the work, and is supported in the position shown above the work by means of supports 17 which also serve to hold bearings 18 for a conveying shaft 19. Each shaft is provided with a sleeve 21, similar to sleeve 13 of the furnace, so that, as the pipes are forwarded through the cooling apparatus, they are kept in proper alignment. Shafts 19 of the cooling units, as well as shafts 12, are driven at the same speed by means, not shown, that may be a common drive or individual motors.

Each of the cooling units is provided at its ends with extensions 20 so that they can be joined together in a gas tight manner. A plate 22, that has an opening 23 in it through which the work travels, is located between each cooling unit, and is held in place -by flanges on the ends of extensions 20. This opening 23 is only slightly larger than the tubes, as is shown in FIG. 3, and in effect forms a restricted orifice between each of the cooling units.

' Coolingatmosphere is blown against the top and the bottom of the tubes passing through the cooling units. For this purpose, there is provided in chamber 16 a sheet metal manifold 24 that has an inlet 25 through which a protective atmosphere is introduced. The manifold extends the length of the chamber through the center portion thereof, and is provided with a plurality of partitions 26 that serve to form passages above each of the pipes being cooled. The lower wall of each passage is provided with an elongated slot 27, so that the atmosphere is discharged against the pipes in the form of a sheet the length of the chamber.

In like fashion, there is provided a second manifold 29 which is used to discharge cooling atmosphere against the bottom of the tube. This manifold is provided with an inlet 31 and with a plurality of partitions 32 which form passages aligned with each of the tubes. The upper ends of these passages are formed by the bottom wall of chamber 16, and are provided with slots 33 through which atmosphere can be forced in sheets against the bottoms of the tubes. These passages, like the upper passages, are provided with dampers 34 so that the flow of atmosphere to the various passages can be equalized. Atmosphere to be circulated is supplied to the manifolds 24 and 29 from a fan 35. The atmosphere exhausts from the slots 27 and 33 into chamber 16 at the sides of manifold 24, and is removed through an outlet 36. The atmosphere travels through a heat exchanger 37 that reduces the temperature of the atmosphere before it moves back to the fan again to be discharged over the tubes. Thus,

Each furnace unit is also provided there is provided a circulating system in each of the cooling units, through which the atmosphere that is used for cooling can be circulated.

As will be noted below, the cooling atmosphere used for cool-ing the tubes is of a reducing or neutral type. This atmosphere is introduced through a pipe 38 on the discharge side of the last cooling unit to flow through the various units in sequence, and be discharged at the left end of the first unit. The cooling atmosphere can be obtained from any conventional atmosphere generator and be piped therefrom to pipe 38 for introduction into the cooling system.

In the following description of the use of the apparatus, it will be assumed that the pipe is being heated for galvanizing. If the .pipe was to be coated with another metal, the operation would be the same, but the pipe would be heated and cooled to ditferent temperatures, depend-ing upon the coating. Pipe, usually pickled to remove mill scale and washed, is placed on conveyor 1 to be moved axially through the apparatus, With the construction shown herein, four pipes can be handled at one time.

The fuel-air ratio of the burners 8 is adjusted so that the furnace atmosphere has no free oxygen. Therefore, at the temperatures to which the pipe is being heated, no scale will be formed, and any slight oxide that will have been on the pipe surface will be removed. The temperature of the furnace and the speed of movement of the pipe therethrough are so correlated that the temperature of the pipe will be between 1250 F. and 1350 F. as it enters the cooling apparatus, and preferably near the lower end of this range. This can be accomplished with a furnace about 80 feet long and at about 2400 F. when the pipe is 1%" in diameter and traveling at about 116 feet per minute. With the other variables being constant, the speed will vary with the size of the pipe. The pipe is discharged from the furnace immediately into the cooling apparatus.

As the pipe moves into the cooling units, it is cooled by the sheets of atmosphere that are blown against it from above and below. This atmosphere is continuously cooled for each cooling unit by the heat exchanger 37 associated therewith. The velocity of the atmosphere and its temperature are so adjusted that the pipe is cooled to a temperature of from 850 F. to 900 F. by the time it is discharged into coating bath 4, which is maintained at a temperature of approximately 870 F. Ordinarily, the pipe will have a temperature slightly higher than that of the coating metal.

The cooling atmosphere that is circulated around the pipes is neutral or slightly reducing in order to preserve or enhance the clean surface of the pipe. This atmosphere is introduced under a slight pressure through pipe 38 between the cooling apparatus and the coating tank, which is closed. As the atmosphere is circulated in the last cooling unit, some of it will flow through opening 23 in plate 22 into the next adjacent cooling unit, and so on, until it is exhausted from the inlet end of the first cooling unit. Each of the openings 23 acts as an orifice to produce a pressure drop between each unit. Therefore, the static pressure in each cooling unit will increase as the pipe travels toward the coating bath, This pressure change will produce a positive flow of atmosphere through the bore of the pipe from the discharge end toward the entrance end of the cooling apparatus. Thus, the bore of the pipe is purged of combustion gases, protected and, in some cases, cleaned as the pipe is being cooled. In addition, the flow of atmosphere through the pipe aids in cooling.

It will be seen, therefore, that I have provided apparatus in which pipes can be prepared for coating on both the interior and exterior surfaces while continuously traveling from a point of supply to a coating bath.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit and scope of the invention set forth in the appended claims, and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

What is claimed is:

1. Apparatus for treating pipe with heat comprising means to move pipes axially through a path, heating means surrounding a first portion of said path, cooling means surrounding a second portion of said path, said cooling means comprising structure forming a plurality of separated chambers, enclosing means including means forming a restricted passage through which .the pipe passes connecting each of said chambers, means associated with each chamber to circulate atmosphere to and from each of said chambers including means to direct the atmosphere against spaced points on the exterior of the pipe, and means to introduce the atmosphere to be circulated into the last of the chambers through which the pipe passes thereby to create a reduced pressure sequentially in the chambers.

2. Apparatus for heating metal tubes for coating comprising a conveyor operative to move a pipe axially through a path, means surrounding a first portion of said path to heat said pipe to a temperature above that at which it is introduced into a coating bath, cooling means surrounding a second portion of said path to cool the pipe to a temperature at which it is introduced into a coating bath, said last means including a plurality of axially displaced and separate units surrounding said conveyor, each unit including means to circulate an atmosphere across pipes traveling through said unit, enclosing means having a restricted orifice through which the pipes travel connecting each of said units, and means to introduce an atmosphere into the last of said units through which the pipes travel, the atmosphere traveling through said orifices to each unit.

3. The combination of claim 2 including a coating bath into which the pipes are discharged by said conveyor, and means extending between the last of said units through which the pipe travels and said coating bath to form an air tight shield around the pipe.

4. In an apparatus for coating pipe including means for forwarding the pipe axially through a path, means sur rounding a first portion of said path to heat said pipe to a temperature above coating temperature, means including a plurality of axially displaced units connected to form a closed path surrounding a second portion of said path to cool said pipe to a coating temperature, each of said units including means to circulate a cooling atmosphere over said pipes, means to supply said cooling atmosphere only to the last of said units through which the pipe passes, said cooling atmosphere flowing from one unit to the other counter to the movement of the pipe, and means between each of said units to form a restriction thereby to create a pressure drop in said cooling atmosphere as it flows between said units.

5. Apparatus for preparing pipes for coating including conveying means to move pipes axially in a path from a point of supply to a coating bath, heating means surrounding a first portion of said path operative to heat the pipes to a temperature above that at which the pipes are coated, cooling means for the pipe including a plurality of individual cooling units connected to form an enclosed passage surrounding a second portion of said path and operative to cool the heated pipe to coating temperature, means to introduce a protective atmosphere only into the last unit through which the pipe travels, said cooling atmosphere flowing from one unit to the other counter to the movement of the pipe, means to create a pressure drop between each unit as the protective atmosphere flows from one unit to the next, and means in 5 each unit individually to circulate the atmosphere around the pipes.

6. The combination of claim 5 including heat exchange means for each unit to reduce the temperature of the circulating atmosphere, and means to direct the circulating atmosphere for each unit through its associated heat exchange means.

References Cited by the Examiner UNITED STATES PATENTS 2,032,744 3/1936 Fessler et al 118-69 X 2,233,474 3/ 1941 Dreffein 226-5 X 2,378,758 6/ 1945 Ekstrom 118-66 2,393,024 1/1946 Cox et a1. 117-49 Lehrer 34-66 X Cook 118-66 X Stromquist 117-49 Dreffein 263-36 Alferieff 117-1 1912 X Webb 15-3062 X Conant 118-69 Heaton et a1 118-66 Nance 118-69 X Holcroft et al 263-36 X DANIEL BLUM, Primary Examiner.

RALPH S. KENDALL, Examiner. 

1. APPARATUS FOR TREATING PIPE WITH HEAT COMPRISING MEANS TO MOVE PIPES AXIALLY THROUGH A PATH, HEATING MEANS SURROUNDING A FIRST PORTION OF SAID PATH, COOLING MEANS SURROUNDING A SECOND PORTION OF SAID PATH, SAID COOLING MEANS COMPRISING STRUCTURE FORMING A PLURALITY OF SEPARATED CHAMBERS, ENCLOSING MEANS INCLUDING MEANS FORMING A RESTRICTED PASSAGE THROUGH WHICH THE PIPE PASSES CONNECTING EACH OF SAID CHAMBERS, MEANS ASSOCIATED WITH EACH CHAMBER TO CIRCULATE ATMOSPHERE TO AND FROM EACH OF SAID CHAMBERS INCLUDING MEANS TO DIRECT THE ATMOSPHERE AGAINST SPACED POINTS ON THE EXTERIOR OF THE PIPE, AND MEANS TO INTRODUCE THE ATMOSPHERE TO BE CIRCULATED INTO THE LAST OF THE CHAMBERS THROUGH WHICH THE PIPE PASSES THEREBY TO CREATE A REDUCED PRESSURE SEQUENTIALLY IN THE CHAMBERS. 